title: DR1769, a protein with N-terminal beta propeller repeats and a low-complexity hydrophilic tail, plays a role in desiccation tolerance of Deinococcus radiodurans.
abstract: The Deinococcus radiodurans genome encodes five putative quinoproteins. Among these, the Δdr2518 and Δdr1769 mutants became sensitive to gamma radiation. DR2518 with beta propeller repeats in the C-terminal domain was characterized as a radiation-responsive serine/threonine protein kinase in this bacterium. DR1769 contains beta propeller repeats at the N terminus, while its C-terminal domain is a proline-rich disordered structure and constitutes a low-complexity hydrophilic region with aliphatic-proline dipeptide motifs. The Δdr1769 mutant showed nearly a 3-log cycle sensitivity to desiccation at 5% humidity compared to that of the wild type. Interestingly, the gamma radiation and mitomycin C (MMC) resistance in mutant cells also dropped by ∼1-log cycle at 10 kGy and ∼1.5-fold, respectively, compared to those in wild-type cells. But there was no effect of UV (254 nm) exposure up to 800 J · m(-2). These cells showed defective DNA double-strand break repair, and the average size of the nucleoid in desiccated wild-type and Δdr1769 cells was reduced by approximately 2-fold compared to that of respective controls. However, the nucleoid in wild-type cells returned to a size almost similar to that of the untreated control, which did not happen in mutant cells, at least up to 24 h postdesiccation. These results suggest that DR1769 plays an important role in desiccation and radiation resistance of D. radiodurans, possibly by protecting genome integrity under extreme conditions.
authors.affiliation: Molecular Biology Division, Bhabha Atomic Research Centre, Mumbai, India.
authors.forename: Yogendra S
authors.initials: YS
authors.lastname: Rajpurohit
authors.forename: Hari S
authors.initials: HS
authors.lastname: Misra
mesh_terms: D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism*; D034301:Deinococcus / Q000187:drug effects / Q000235:genetics / Q000502:physiology* / Q000528:radiation effects; D003890:Desiccation; D005720:Gamma Rays; D017353:Gene Deletion; D050296:Microbial Viability / Q000187:drug effects / Q000528:radiation effects; D016685:Mitomycin / Q000633:toxicity; D013312:Stress, Physiological; D014466:Ultraviolet Rays
chemical_list: D001426:Bacterial Proteins; D016685:Mitomycin